The present invention relates generally to power tools and more particularly to an air-operated ratchet tool.
Ratchet tools which are hand held and driven by an air motor are well known. Such tools typically include a housing having a fork at one end within which is disposed a rotatable drive body for loosening and tightening fasteners.
In current air ratchet tools, the air motor is located within the housing such that vibrations of the motor which occur during operation of the tool are transferred to the housing, thereby undesirably causing vibration of the tool while it is in the user's hand. Furthermore, the motor is located within the housing such that cold air produced by the motor during operation causes the housing to become cold, thereby undesirably causing the surface of the tool to become cold while it is in the user's hand.
A ratchet tool includes a knob which is rotatable between fastener-tightening and fastener-loosening positions. However, the knob of currently available tools has a tendency to undesirably move between these positions during use, whereupon a fastener would be loosened even though the knob had been set to tighten the fastener or vice versa.
Since the knob of current ratchet tools extends outwardly from the surface of the housing, it is susceptible to blows which result when the tool is dropped. The shock of the blow to the knob is transferred to the housing, thereby undesirably increasing the risk of damage to the housing in the form of stress cracks or the like.
When a ratchet tool is operated, there is a tendency to oscillate if there is not enough friction between the fastener and the work piece. The ratchet tool typically includes a mechanism associated with the drive body to prevent such slippage from occurring by providing friction between the drive body and the fork or by providing another ratcheting mechanism between the drive body and the housing or by roller clutching. Such friction has been provided by coil springs and pins. This type of mechanism, however, is disadvantageous because it undesirably causes grooves to be formed in the forks.
Additionally, current ratchet tools include a manifold in the housing which provides inlet air to the motor and receives exhaust air from the motor. The pulsating flow of the exhaust air out of the motor causes the creation of Helmholtz frequencies, resulting in undesirable operating noises.
In some current ratchet tools, a bushing is disposed in an opening in one arm of the fork. The bushing surrounds the drive body and is used for the transfer of operating loads from the drive body to the housing via the one fork arm. The bushing, however, is often not securely fit and accurately located within the opening of its associated fork arm such that it has a tendency to be rotated with the drive body or not aligned with the base of the other fork arm. As a result, operating loads are not effectively transferred from the drive body to the housing.
The housing of currently available ratchet tools is comprised of three axially segmented members within which all of the elements of the tool are located. With axial segmentation, the manufacturing and assembly process is necessarily complicated since it is difficult to machine internal geometries accurately and locate and align each of the elements within the housing. Further, it is difficult to gain access to the elements in the event that repair of the tool is needed.